Early Developmental Milestones
Infants, toddlers, and young children with Tetrasomy 18p may develop more slowly than those without Tetrasomy 18p. For example, it may take a little longer for them to learn how to roll over, sit, crawl, and walk. It may also take longer for them to reach for and grab toys, hold a bottle, and to feed themselves. Language skills may also develop later than their peers. On average, babies with Tetrasomy 18p roll over at about seven months, and walk and say their first words at about 2½ years. It is important to remember that these numbers are averages. This means that some babies with Tetrasomy 18p will reach their milestones earlier than these averages while others reach their milestones later.
People with Tetrasomy 18p have some degree of cognitive impairment. This means that they have difficulty performing various mental tasks. This can include things like reading, writing, and other types of activities that require mental processes to complete. Cognitive ability is typically measured using IQ tests.
The degree of impairment varies among individuals with Tetrasomy 18p. Based on standardized testing, people with Tetrasomy 18p typically have IQ scores in the moderate range of impairment.
Cognitive abilities are not the only thing that may affect an individual’s ability to perform certain tasks. Executive functions also play an important role in a person’s ability to function well within their community.
Executive functions are a group of brain based processes that guide, direct, and manage cognitive, emotional, and behavioral activities. Executive functions are different from instinctual behaviors where something in the environment triggers a response. For example, a bright light shined in the eye (stimulus) triggers the response (quickly close the eyelid). This response is automatic and does not require conscious thought. In contrast, executive functions serve as a moderator or middle point between the stimulus and the response. Executive functions can monitor, slow down/stop or initiate behaviors, and provide time for internally-based self-talk and reasoning/rationalizing to occur.
Dr. Russell Barkley, a pioneer in ADHD research, uses a metaphor to give a visual image of executive functions in action. In his metaphor, he compares executive function to the conductor’s role in an orchestra. “The conductor organizes various instruments to begin playing singularly or in combination, integrates the music by bringing in and fading certain actions, and controls the pace and intensity of the music”.
Many individuals with Tetrasomy 18p have some deficits in the area of executive functions. The table below lists some of the issues that may impact children with Tetrasomy 18p, based on data collected from 20 children.
Adults with Tetrasomy 18p may also experience difficulties in the area of executive functioning. The chart below is based on data collected from 14 adults.
In addition to the concerns noted above, people with Tetrasomy 18p might have some difficulties with social interactions. The range of social impairment vary tremendously. For example, some have been diagnosed with severe autism. Others have moderate forms of Autism Spectrum Disorder (ASD). Others have mild difficulties with reciprocal social behavior that may interfere (mildly or moderately) in daily social interaction. The table below lists the areas that may be of concern to children and adults with Tetrasomy 18p.
Personality and Behavior
Children and adults with Tetrasomy 18p may have some unique behavioral traits.
There are several different scales and evaluations that measure behavioral traits. Behaviors can be measured as internalizing (a negative behavior), externalizing (a negative behavior), and adaptive skills (a positive behavior). Some examples of internalizing behaviors include anxiety, depression, and somatization (when psychological concerns present as physical symptoms). Some examples of externalizing behaviors include aggression, hyperactivity, and conduct problems. Some examples of adaptive skills include activities of daily living, functional communication, and social skills.
The table below lists the areas where children with Tetrasomy 18p may struggle based on data collected from 33 children. It also lists the areas where they do not seem to have any difficulties.
Based on data from the Chromosome 18 Clinical Research Center, adults with Tetrasomy 18p also may also struggle behaviorally. As shown in the table below, there are many areas that do not seem to be impacted.
Education and Living Situation
Many families wonder what the future holds for their child with Tetrasomy 18p. Although it is impossible to predict the outcome for an individual, it is helpful to know what other adults with Tetrasomy 18p have experienced. The Chromosome 18 Clinical Research Center has recently published data on adults with Tetrasomy 18p.
Twelve adults with Tetrasomy 18p were included in the paper. The majority lived with their parents. All twelve were either in high school or graduated high school with the help of special education classes. One had a vocational degree, and another was attending college. The majority were engaged in either volunteer or paid work. It is important to note that the average age of this group of adults is 25.6 years. Typical young adults of this age with normal chromosomes often still live with their parents.